1. Field of the Invention
The present invention relates to medical devices and, more specifically, to a device for transporting radio-pharmaceuticals used in positron emission tomography.
2. Description of the Prior Art
Positron emission tomography (PET) imaging is a diagnostic examination that involves acquiring physiologic images based on the detection of positron radiation. Positrons are particles emitted from radioactive substances. The radioactive substances used are injected into a patient and positrons from the radioactive substance are detected and imaged by a PET scanner. The resulting images are used to evaluate a variety of diseases.
Pharmaceutical compositions used in PET scans are administered in liquid form by injection into the patient. Radio-pharmacists typically calculate a unit dose based on the amount of decay that a dose will undergo during transport to the hospital at which the dose will be administered. In preparing the dose, the radio-pharmacist places the dose into a syringe and then places the syringe into a “pig” that shields those handling the dose from the radioactive contents of the syringe. The pig is then transported to the hospital for administration to a patient.
With many types of radio-pharmaceuticals, a lead pig is sufficient to shield those handling the dose. However, for radio-pharmaceuticals designed for PET scans, a typical lead-shielded pig does not provide sufficient protection by itself To compensate, existing PET radio-pharmaceutical transport systems require an extra level of shielding. This is accomplished by providing a secondary shielded case for the pig. Such a shielded case includes lead shielding about a cylindrical opening into which the pig fits.
Existing PET radio-pharmaceutical pigs tend to need to be replaced on a regular basis. This is because the shielding quality of lead breaks down in the presence of PET pharmaceutical radiation. Thus, the cost is increased. Also, there is a danger of insufficient protection if a radio-pharmacist continues to use a pig past its designed life span.
Because most pigs are roughly cylindrical in shape, rolling of such pigs is a problem If a pig is allowed to roll, it could roll off of the surface on which it is placed and fall, causing injury, destroying the dose of the radio-pharmaceutical composition contained therein, or both. Some existing pigs include a flat surface milled into the outer surface of the pig. The milling is done by removing several exterior chords of the cylinder forming the pig, thereby forming flat surfaces. Also, several small evenly-spaced bumps may be added to the exterior surface of the pig. Both of these methods of preventing rolling may be satisfactory for ordinary conditions, but they do not provide a sufficient anti-roll capability in situations in which a pig is accidentally bumped with considerable force. Furthermore, most pigs include two sections that must be separated when accessing the syringe inside. However, many existing pigs usually include anti-roll texturing on only one section. Thus, if the section without the anti-roll texturing is placed on a table, it may roll off and cause injury.
Typical radio-pharmaceutical pigs have an inner chamber into which a filled syringe is placed. A plastic liner is frequently employed to prevent spillage from the syringe from accumulating inside the pig. Such a liner is typically made from rigid plastic and used only once. Because the liner is rigid, it takes up a considerable amount of space to store and to dispose of.
Typically, when administering a radio-pharmaceutical to a patient, the syringe is removed from the pig and placed in a shielded holder that protects the physician's hands from radiation while injecting the radio-pharmaceutical into an IV bag. The transfer of the syringe causes a brief exposure to the user and increases the risk that the syringe could fall and be harmed.
Therefore, it would be desirable for a radio-pharmaceutical pig to be capable of providing a mechanism for administering a radio-pharmaceutical without having to transfer it to a shielded holder.